Analysis of moving fluids

ABSTRACT

The invention concerns the analysis of moving fluids which may be slurries or the like. According to the invention the fluid to be analysed flows under pressure through an orifice at such a rate that it forms a clearly defined jet. Thus non-contact means such as an X-ray device can be used to analyse the fluid without the need of a window between the analysis means and the fluid. Means are provided both for determining the flow rate of the fluid in the jet and its dimensions so that the non-contact analysis means can be protected from damage should the flow rate or the dimensions of the jet vary beyond predetermined limits.

States Patent [191 Carr-rion Dec.9,1975

[ ANALYSIS OF MOVING FLUIDS [75] Inventor: Kenneth Garfield Carr-Brion,

Stevenage, England [73] Assignee: National Research DevelopmentCorporation, London, England [22] Filed: Mar. 11, 1974 [21] Appl. No.:450,233

Related US. Application Data [63] Continuation-impart of Ser. No.292,786, Sept. 27,

1972, abandoned.

[30] Foreign Application Priority Data Oct. 4, 1971 United Kingdom46105/71 Oct. 3, 1972 Germany 2248505 [52] US. Cl. 250/272; 250/432;250/514 [51] Int. Cl. G01N 23/20 [58] Field of Search 250/272, 273, 428,432, 250/435, 460, 514, 515

[56] References Cited UNITED STATES PATENTS 3,581,085 5/1971 Barrett250/301 3,666,943 5/1972 Carr-Brion et a] 250/272 FOREIGN PATENTS ORAPPLICATIONS 648,484 1/1951 United Kingdom Primary ExaminerDavis L.Willis Attorney, Agent, or FirmCushman, Darby and Cushman [57] ABSTRACTThe invention concerns the analysis of moving fluids which may beslurries or the like. According to the invention the fluid to beanalysed flows under pressure through an orifice at such a rate that itforms a clearly defined jet. Thus non-contact means such as an X-raydevice can be used to analyse the fluid without the need of a windowbetween the analysis means and the fluid. Means are provided both fordetermining the flow rate of the fluid in the jet and its dimensions sothat the non-contact analysis means can be protected from damage shouldthe flow rate or the dimensions of the jet vary beyond predeterminedlimits.

10 Claims, 3 Drawing Figures 75 A/acZem/c /7asurm g l7 Syszem US. PatentDec. 9, 1975 Sheet 1 of2 3,925,661

Feed from 00/25/012! I v 10 75 Nacleo/z/c fleasurmy 7 System fn ut fromtank level pressure orftou sensor 7 US. Patent Dec. 9, 1975 Sheet 2 of23,925,661

ANALYSIS OF MOVING FLUIDS This is a continuation-in-part application ofUS. application Ser. No. 292,786, filed Sept. 27, 1972, now abandoned.

The present invention concerns the determination of elements in flowingsystems.

This is frequently done by x-rays fluorescence and is particularlyimportant in the analysis of mineral slurries. Thus radioisotope x-rayfluorescence analysis has been successfully applied to the on-streamdetermination in slurries of a number of elements such as calcium, zincand tin. In known x-ray fluorescence systems for mineral slurries anx-ray transparent window is located between the flowing sample and thex-ray system. One main function of the window is to produce a relativelyflat sample surface at a constant distance from the x-ray system. Thisis in fact essential for quantative analysis. Another function is toprotect the x-ray from the fluid.

However, such known systems have considerable disadvantages. The window,which must be very thin to allow the transmission of very low energycharacteristic x-rays, is subject to abrasion, deposition, chemicalattack, non-elastic deformation and degradation under high x-rayintensities. Furthermore, even when the window is as thin as abrasionand pressure variations permit, it strongly absorbs the characteristicx-rays from lighter elements such as aluminium, making theirdetermination in flowing fluids difficult or impossible by x-rayfluorescence. However, in British patent specification No. 1,232,581,which is concerned with measuring the purity of fuel oil, a method ofcontactless analysis of oil is disclosed in which a jet of oil is passedthrough ultraviolet radiation and any subsequent fluorescence isdetected so that impurities can be measured without actual contact beingmade. Nevertheless, the handling of fuel oil is a substantially easierundertaking than the mineral slurries with which the present inventionis concerned. In particular the greater mass corrosiveness and theparticulate nature of the mineral slurries means that should the streamof slurry spread beyond its intended boundaries during analysisconsiderable damage could be caused to the detection equipment.

The present invention has for an object to substantially reduce thepossibility of such expensive damage occurring.

Three embodiments will now be described by way of example and withreference to the accompanying drawings in which:

FIG. 11 is a section through one embodiment of an x-ray fluorescentsystem constructed in accordance with the present invention;

FIG. 2 is a similar view of a second embodiment also constructed inaccordance with the present invention, and

FIG. 3 shows a third embodiment.

In the Figures of the accompanying drawings, like integers will bedesignated by like reference numerals. FIG. 1 of the accompanyingdrawings shows an x-ray fluorescence analysis system in which fluid lflows vertically down through a pipe 2 having'an orifice 3 of reducedcross-sectional area. The fluid l is pumped by a suitable pump having asmooth rate of delivery or fed from a constant head tank. The orifice 3is smoothly contoured and in cross section is in the shape of an 2elongated ellipse. The pipe 2 is made of any suitable material such aspolythene and the orifice itself is made from a suitably wear resistantmaterial such as neoprene or silicon carbide. An x-ray system 4 ismounted as close as possible to the orifice 3. The reason for this isthat the surface of the jet of fluid is subject to large random andnon-random variations in its position as the distance from the orifice 3is increased. A non-dispersive x-ray system 4 has an x-ray source 5 andan associated detector 6 which gives an output on an output line 7 to astandard nucleonic measuring system which is not shown. Thenon-dispersive x-ray system 4 is conventional in nature. An on-streamenergy dispersive analyser for x-ray fluorescence is described in thearticle by K.G.Carr-Brion in X-ray Spectrometry 2, 1973. In order toprotect the x-ray system 4 from splashes when the rate of flow of thefluid is insufficient to form a clearly defined jet, a pressue or flowsensor 8 is provided on the pipe 2 a suitable distance upstream from theorifice 3. This sensor 8 controls an actuator 9 which in turn controls ashutter 10 which protects the face of the x-ray system 4 and which ismoved away by the actuator 9 only when the sensor 8 gives an outputsignal indicating that the fluid pressure is sifficiently high and hasbeen so for a preselected delay time.

In addition to measurement of the rate of flow of the fluid to beanalysed means are also provided to detect if the dimensions of thestream passing the analytic equipment vary beyond predetermined limits.Such variation might be caused by an obstruction or a sudden change inthe shape of the orifice 3 caused by a breakage.

Thus instability of the jet stream is detected by a pair ofphoto-electric sensors 20, 21. A light source 22 illuminates an edge ofthe jet and casts a shadow in the plane containing the photoelectricsensors 20, 21 so that should the width of the jet be correct in theplane of the sensors the edge of the shadow lies between the twosensors. The outputs of sensors 20, 21 are taken to comparators 23, 24so that if the output of sensor 20 drops below a predetermined levelcaused by a widening of the jet the comparator 23 gives an output to arelay 25 to actuate the safety shutter 10.

Similarly if the output of sensor 21 rises due to the jet narrowing,comparator 24 gives an output to a further relay 26. again actuating thesafety shutter 10. Thus an abnormal output from either sensor causesclosure of the shutter 10. Should the output of a sensor return tonormal after closure of the shutter 10 a delay circuit 27 is provided sothat the shutter 10 is only opened after a predetermined delay. Thecomparators, delay circuit and relays are all conventional in design.

Naturally, by the addition of further pairs of sensors, comparators andrelays, checks can be made in every dimension of the jet. In such a casea gate circuit of well known design would be provided so that abnormalreading from any single sensor would actuate closure of the shutter 10.The second embodiment, illustrated in FIG. 2, is identical to theembodiment of FIG. 1 save that the pipe 2 is bent through a right-angleso that the jet extends approximately horizontally. In this embodimentgravity affects the position of the jet if the flow rate variesappreciably and the jet must be fed by a system giving an approximatelyconstant flow rate such as a constant head tank.

FIG. 3 shows a third embodiment incorporating a second system by meansof which the x-ray detector 6 can be protected. In this embodiment thedetector 6 is mounted on a lever 30 pivoted at 31 and coupled to adouble-acting hydraulic ram 32. In this embodiment integers similar tothose of the embodiment of FIGS. 1 and 2 have the same referencenumerals. Thus should the rate of flow of the jet fall below aparticular value or the dimensions of the jet vary outside predeterminedlimits, the ram 32 is actuated to swing the detector 6 away from thecircuitry of the jet and will not return the detector to its operativeposition until all the readings from the various sensors have returnedto normal for a predetermined period.

In all the embodiments the jet of fluid 1 after passing the x-ray system4 falls into a jet trap 11 which is arranged to prevent back-splashingof the x-ray system. The fact that the system of FIG. 1 employs deliveryof the fluid has the advantage that the position of the jet is notaffected by gravity and adequate positional stability can be achieved byfeeding the jet directly from a pump giving relatively smooth delivery.

Although the shape of the orifice has been described as an elongatedellipse in cross-section, the actual shape is not critical providedthere is a smooth transition from the round section of the pipe 2 to theorifice and the absence of scratches and other defects in the internalsurface of the orifice.

The systems described may be used for the analysis of flowing liquids,liquid/solid, gas/solid, gas/liquid and gaseous systems. In a typicalsystem for analysing the contents of a slurry of density about 1.2, aclearly defined jet can be obtained by arranging the slurry to have aflow rate in the range of 1500 to 3000 liters per hour through anelliptical orifice having axes of l and 3.5cm. Naturally the flow rateand the size and shape of the orifice can vary widely in accordance withthe substances being analysed.

Although the system has been described with particular reference tox-ray fluorescence, it has possible applications in analysis by emissionspectography, by infra-red absorption, by diffuse reflection or by x-rayabsorption.

I claim:

1. Apparatus for the analysis of a parameter of a moving fluidcomprising means for passing said fluid through an orifice shaped toprovide a fluid jet of defined dimensions; analyzing means comprising adetector of electromagnetic radiation, said detector being positioned innon-contacting proximity to said jet adjacent the orifice for receivingradiation travelling from said jet to produce a signal varying as afunction of said parameter of said fluid; flow sensor means mountedadjacent said orifice for measuring the rate of flow of said fluidthrough said orifice; and means connected to said flow sensor means andoperative to protect said detector should the rate of flow of said fluidfall below a predetermined value as indicated by said flow sensor means.

2. Apparatus as claimed in claim 1, and including a light source forilluminating at least a portion of said jet, photo-sensitive meanspositioned to receive light from said light source, and comparator meansoperative on variation of the output of said photo-sensitive meanscaused by variation in the radial dimensions of said jet to actuate saidmeans for protecting said detector.

3. Apparatus as claimed in claim 2 wherein said photo-sensitive meanscomprise a pair of photo-sensitive detectors each connected to anindividual comparator, one of said photo-sensitive detectors being sopo- 4 sitioned that said jet will obscure it from said light source whenthe jet has the requisite dimensions and the other photo-sensitivedetector being positioned so that it is illuminated by said light sourcewhen said jet has the requisite dimensions.

4. Apparatus as claimed in claim 1 wherein said means for protectingsaid detector comprises a shutter mounted for movement adjacent said jetfrom a withdrawn position to a protect position between said jet andsaid detector and actuating means operable on receipt of a signal fromsaid flow rate sensor to cause said shutter to move from said withdrawnto said protect position.

5. Apparatus as claimed in claim 1 wherein said detector is an x-raydetector and said analysing means fur ther comprises an x-ray sourcedisposed for irradiating said jet to excite fluorescent x-rays whichwill be received by said detector.

6. Apparatus for the analysis of a parameter of a moving fluidcomprising means for passing said fluid through an orifice shaped toprovide a fluid jet of defined dimensions; analyzing means comprising adetector of electromagnetic radiation, said detector being positioned innon-contact proximity to said jet adjacent the orifice for receivingradiation travelling from said jet to produce a signal varying as afunction of said parameter of said fluid; flow sensor means mountedadjacent said orifice for measuring the rate of flow of said fluidthrough said orifice; a light source for illuminating at least a portionof said jet; photosensitive detector means arranged to receive lightfrom said light source in such a manner that any variations in theradial dimensions of said jet greater than predetermined values causesthe output of said photosensitive detector means to vary; comparatormeans for comparing the output of siad photosensitive detector means;means operative to protect said detector from said jet; means foractuating said protective means in the event of either a fall in theflow rate of said jet detected by said flow sensor means or a variationin the radial dimensions of said jet as detected by said photosensitivedetector means; means for withdrawing said protective means from saiddetector should the outputs of said flow sensor means and saidphotosensitive detector means return to within normal limits.

7. Apparatus as claimed in claim 6 and further including delay means fordelaying the withdrawal of said protective means for a predeterminedperiod after the outputs of said flow sensor means and saidphotosensitive detector means return to within said normal limits.

8. Apparatus as claimed in claim 6 wherein said photosensitive detectormeans comprise a pair of photosensitive detectors, one of saidphotosensitive detectors being so positioned that said jet will obscureit from said light source when the jet has the requisite dimensions andthe other photosensitive detector being positioned so that it isilluminated by said light source when said jet has the requisitedimensions.

9. Apparatus as claimed in claim 6 wherein said means for protectingsaid detector comprises a shutter and actuating means operable onreceipt of a signal either from said flow rate sensor or saidphotosensitive detector means to interpose said shutter between said jetand said detector.

10. Apparatus as claimed in claim 6 wherein said detector is an x-raydetector and said analysing means further comprise an x-ray sourcedisposed for irradiating said jet to excite fluorescent x-rays whichwill be receivecl by said detector.

1. Apparatus for the analysis of a parameter of a moving fluidcomprising means for passing said fluid through an orifice shaped toprovide a fluid jet of defined dimensions; analyzing means comprising adetector of electromagnetic radiation, said detector being positioned innon-contacting proximity to said jet adjacent the orifice for receivingradiation travelling from said jet to produce a signal varying as afunction of said parameter of said fluid; flow sensor means mountedadjacent said orifice for measuring the rate of flow of said fluidthrough said orifice; and means connected to said flow sensor means andoperative to protect said detector should the rate of flow of said fluidfall below a predetermined value as indicated by said flow sensor means.2. Apparatus as claimed in claim 1, and including a light source forilluminating at least a portion of said jet, photo-sensitive meanspositioned to receive light from said light source, and comparator meansoperative on variation of the output of said photo-sensitive meanscaused by variation in the radial dimensions of said jet to actuate saidmeans for protecting said detector.
 3. Apparatus as claimed in claim 2wherein said photo-sensitive means comprise a pair of photo-sensitivedetectors each connected to an individual comparator, one of saidphoto-sensitive detectors being so positioned that said jet will obscureit from said light source when the jet has the requisite dimensions andthe other photo-sensitive detector being positioned so that it isilluminated by said light source when said jet has the requisitedimensions.
 4. Apparatus as claimed in claim 1 wherein said means forprotecting said detector comprises a shutter mounted for movementadjacent said jet from a withdrawn position to a protect positiOnbetween said jet and said detector and actuating means operable onreceipt of a signal from said flow rate sensor to cause said shutter tomove from said withdrawn to said protect position.
 5. Apparatus asclaimed in claim 1 wherein said detector is an x-ray detector and saidanalysing means further comprises an x-ray source disposed forirradiating said jet to excite fluorescent x-rays which will be receivedby said detector.
 6. Apparatus for the analysis of a parameter of amoving fluid comprising means for passing said fluid through an orificeshaped to provide a fluid jet of defined dimensions; analyzing meanscomprising a detector of electromagnetic radiation, said detector beingpositioned in non-contact proximity to said jet adjacent the orifice forreceiving radiation travelling from said jet to produce a signal varyingas a function of said parameter of said fluid; flow sensor means mountedadjacent said orifice for measuring the rate of flow of said fluidthrough said orifice; a light source for illuminating at least a portionof said jet; photosensitive detector means arranged to receive lightfrom said light source in such a manner that any variations in theradial dimensions of said jet greater than predetermined values causesthe output of said photosensitive detector means to vary; comparatormeans for comparing the output of siad photosensitive detector means;means operative to protect said detector from said jet; means foractuating said protective means in the event of either a fall in theflow rate of said jet detected by said flow sensor means or a variationin the radial dimensions of said jet as detected by said photosensitivedetector means; means for withdrawing said protective means from saiddetector should the outputs of said flow sensor means and saidphotosensitive detector means return to within normal limits. 7.Apparatus as claimed in claim 6 and further including delay means fordelaying the withdrawal of said protective means for a predeterminedperiod after the outputs of said flow sensor means and saidphotosensitive detector means return to within said normal limits. 8.Apparatus as claimed in claim 6 wherein said photosensitive detectormeans comprise a pair of photosensitive detectors, one of saidphotosensitive detectors being so positioned that said jet will obscureit from said light source when the jet has the requisite dimensions andthe other photosensitive detector being positioned so that it isilluminated by said light source when said jet has the requisitedimensions.
 9. Apparatus as claimed in claim 6 wherein said means forprotecting said detector comprises a shutter and actuating meansoperable on receipt of a signal either from said flow rate sensor orsaid photosensitive detector means to interpose said shutter betweensaid jet and said detector.
 10. Apparatus as claimed in claim 6 whereinsaid detector is an x-ray detector and said analysing means furthercomprise an x-ray source disposed for irradiating said jet to excitefluorescent x-rays which will be received by said detector.